Benzannulated 6,5-Spiroketals from Donor–Acceptor Cyclopropanes

Gai, Sinan; Lucas, Nigel T.; Hawkins, Bill C.

doi:10.1021/acs.orglett.9b00878

Cited by 15 publications

(6 citation statements)

References 55 publications

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“…In 2019, the Hawkins group reported an efficient synthesis of benzannulated 6,5-spiroketals 9 from vinyl 1,1-diacylcyclopropanes 7 (Scheme 4). 25 The in situ generated VCPs 7 undergo Pd(0)-catalyzed C−C bond cleavage to form π-allyl intermediates 8, followed by ring closure to afford spiroketal complexes 9 in good yields. However, the products were isolated as a 1:1 mixture of diastereomers with the relative stereochemistry set except at the vinyl group, but both isomers could be readily separated by column chromatography.…”

Section: C−c Bond Cleavage Of Activated Vcpsmentioning

confidence: 99%

Transition Metal-Catalyzed Selective Carbon–Carbon Bond Cleavage of Vinylcyclopropanes in Cycloaddition Reactions

et al. 2020

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In this review, transition metal-catalyzed methodologies and applications that exploit C−C bond cleavage of vinylcyclopropanes (VCPs) are summarized with a focus on cycloaddition and related addition reactions. Transition metals, including palladium, nickel, iron, ruthenium, rhodium, cobalt, and iridium, can catalyze the cleavage of C−C bonds in activated or nonactivated VCPs. Additionally, these bond-breaking reactions can occur as intraor intermolecular processes. The properties of activated and nonactivated VCPs are discussed in the Introduction. Various transition metal-catalyzed cycloaddition and addition reactions involving the cleavage of C−C bonds in activated VCPs are then discussed in the next chapter. The transition metal-catalyzed cycloadditions involving the cleavage of C−C in nonactivated VCPs are summarized in the following chapter. Finally, challenges and potential opportunities are outlined in the last chapter.CONTENTS 3.3. Applications 131 4. Conclusions and Outlook 133

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Section: C−c Bond Cleavage Of Activated Vcpsmentioning

confidence: 99%

Transition Metal-Catalyzed Selective Carbon–Carbon Bond Cleavage of Vinylcyclopropanes in Cycloaddition Reactions

et al. 2020

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“…As an extension of the work of Hawkins and co-workers towards the synthesis of chromones, the capacity for this reaction to be expanded to the preparation of 6,5-benzannulated spiroketal products was reported (Scheme 35). 67 Of note was the one-pot preparation of 6,5-spirocyclic core of berkelic acid 140 in excellent yield from a diketone which was converted into cyclopropane 138 in situ. Mechanistically, this reaction is proposed to proceed through the intermediate 139 after deallylation of the phenol functionality and ring-opening of the cyclopropane via -allyl formation.…”

Section: Short Review Syn Thesismentioning

confidence: 99%

The Bonding and Reactivity of α-Carbonyl Cyclopropanes

Craig¹,

Hawkins

2019

Synthesis

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The cyclopropane functionality has been exploited in a myriad of settings that range from total synthesis and methodological chemistry, to medical and materials science. While it has been seen in such a breadth of settings, the typical view of the cyclopropane moiety is that its reactivity is derived primarily from the release of ring strain. While this simplified view is a useful shorthand, it ignores the specific nature of cyclopropyl molecular orbitals. This review aims to present the different facets of cyclopropane bonding by examining the main models that have been used to explain the reactivity of the functionality over the years. However, even with advanced theory, being able to precisely predict the reactivity of an exact system is nigh impossible. Specifically chosen, carbonyl-bearing cyclopropyl species act as so-called acceptor cyclopropanes and, if correctly derivatised, donor–acceptor cyclopropanes. By undertaking a case study of the history of carbonyl cyclopropanes in organic synthesis, this review highlights the relationship between the understanding of theory and pattern recognition in developing new synthetic methods and showcases those successful in balancing this critical junction.1 Cyclopropanes2 The Strain Model3 The Forster–Coulsin–Moffit Model4 The Walsh Model5 Acceptor, Donor, and Donor–Acceptor Cyclopropanes6 Reactions of Carbonyl Cyclopropanes

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“…B. C. Hawkins Thanks to the hard work of my research group, we have developed several useful synthetic methods to access important compound classes such as oxazinones, 1,2 chromones 3 and benzannulated spiroketals. 4 However, my group's synthesis of the marine natural product spiroleucettad ine (Fi-gure 2) is probably the most important achievement of my independent career to date. 5,6 This synthes is has enabled access to large quantities of spiroleucettadine and the subsequent uncovering of unexpected biological activity, which in turn has led us to pursue a medicinal chemistry program focused on establishing a structure-activity relationship and also, with the help of collaborators, efforts have begun to establish the mechanism of action of spiroleucettadine.…”

Section: Literature Coverage Synformmentioning

confidence: 99%

Synform Issue 2020/1

Zanda¹

2019

Synthesis

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Are you ready for the new decade? SYNFORM certainly is! In the era of research visibility and public outreach, SYNFORM-supported by the Thieme Chemistry journals and social media-has become a powerful tool for reaching increasingly larger audiences with your publications and is entering its third decade in sparkling form and more ambitious than ever! In case you had any doubts, just look at the content of this first issue of 2020: I am really pleased that the decadeopening article comes from India, which is taking giant leaps in chemistry, as apparent from the excellent work pre sented by Koley and Maji on B(C 6 F 5) 3-promoted synthesis of triaryl-1,2,4-triazoles. The second article of the decade is Q. Song's (P. R. of China) elegant stereoconvergent synthesis of ketoximes. The third article is from the lab of an absolute heavyweight of organic chemistry: Prof. K. Barry Sharpless. In this case, sup ported by J. Dong (P. R. of China), who co-authored a new chapter of the click-chemistry saga recently published in Nature. Finally, the first Young Career Focus interview of the decade takes us to the Anti podes, where B. C. Hawkins (New Zealand) tells us about his molecular targets in organic synthesis. You can tell it's gonna be a good decade!! Enjoy your reading!!! In this issue Literature Coverage Acceptorless Dehydrogenative Cyclization of N-Tosylhydrazones and Anilines: Dual Role of B(C 6 F 5

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Benzannulated 6,5-Spiroketals from Donor–Acceptor Cyclopropanes

Abstract: A rapid and facile synthesis of benzannulated 6,5-spiroketals from vinyl 1,1-diacylcyclopropanes is reported. The method utilizes mild reaction conditions with good to excellent yields and high diastereoselectivity. This methodology was then used to construct the core of berkelic acid.

Cited by 15 publications

References 55 publications

Transition Metal-Catalyzed Selective Carbon–Carbon Bond Cleavage of Vinylcyclopropanes in Cycloaddition Reactions

Transition Metal-Catalyzed Selective Carbon–Carbon Bond Cleavage of Vinylcyclopropanes in Cycloaddition Reactions

The Bonding and Reactivity of α-Carbonyl Cyclopropanes

Synform Issue 2020/1

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